1. Turn Instant Pot on to satue. In a small bowl mix together, ketchup, brown sugar, tomato paste, mustard, vinegar, chili powder, and Worcestershire then set aside.
2. When Instant Pot is hot, add in hamburger and garlic.
3. Cook until meat starts to brown then drain fat.
4. Add meat back into the pot. Add celery, peppers, and onion. Cook for 1-2 minutes until fragrant.
5. Turn Instant Pot off and add ketchup mixture and beef broth.
6. Cook on manual high pressure for 7 minutes. Quick release when the timer is up.
7. In a small bowl, mix together water and corn starch.
8. Turn Instant Pot back onto satue and add corn starch mixture. Cook for 1-2 minutes until sauce becomes thick.
9. Give everything a nice stir then serve on buns.